One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10)(11,14)(12,20)(13,19)(15,17)(16,22)(18,24)(21,23)(25,26)(27,30)(28,31)(29,32)(33,37)(34,38)(35,39)(36,40) involution — undirected(2,5)(6,8)(9,11,14,10)(12,21,23,20)(13,19,15,17)(16,24,18,22)(25,27,29,35)(26,30,32,39)(28,36,37,34)(31,40,33,38)(1,3)(2,6)(4,7)(5,8)(9,12,14,23)(10,16,11,18)(13,24,15,22)(17,21,19,20)(26,31)(28,37)(30,38)(32,33)(34,36)(39,40)(3,7)(6,8)(9,13,14,15)(10,17,11,19)(12,22,23,24)(16,20,18,21)(26,32)(30,39)(31,33)(38,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.